Comparison of RNA extracts from in vitro shoot tip cultures of leafroll-affected and leafroll-free grapevine cultivars

The RNA content of in vitro shoot tip cultures from grapevine leafroll (GLR) disease-affected grapevines was analyzed and compared to that of similar cultures from GLR-free grapevines. A previously unreported low-molecular-weight single-stranded RNA (LMWssRNA) was detected in in vitro shoot tip cultures of 65 % (11 out of 17) of GLR-affected cultivars. This LMWssRNA was absent from disease-free cultivars and may be associated with a virus or a strain of a virus responsible for GLR. Numerous high-molecular-weight (HMW) dsRNA bands were also detected in GLR-affected grapevine cultivars. The intensities and mobilities (apparent molecular weights) of these dsRNA bands varied considerably from one GLR-affected cultivar to the next, but were reproducible for each cultivar. The detection of multiple distinctive RNA banding patterns is consistent with the possibility that more than one agent can cause grapevine leafroll disease

Mechanical sap transmission of a closterovirus from in vitro shoot tip cultures of a leafroll-affected grapevine to Nicotiana benthamiana

Transmission manuelle d'un clostérovirus au Nicotiana benthamiana à partir de cultures in vitro d'une vigne atteinte de l'enroulementDes cultures in vitro d'une vigne de Vitis vinifera Limberger atteinte de l'enroulement ont été broyées dans une solution tampon contenant de la nicotine. Les extraits ont été inoculés sur des feuilles de Nicotiana benthamiana et de 6 autres espèces de plantes herbacées. 3 semaines plus tard, seuls les plants de N. benthamiana ont démontré des symptômes. Ceux-ci consistaient d'un nanissement systémique accompagné d'un éclaircissement des nervures qui se transformait en chlorose interveinale. Les feuilles de ces N. benthamiana contenaient le virus A de la vigne (GVA), démontré par la méthode ISEM

Double-stranded RNA from rupestris stem pitting-affected grapevines

Nucleic acids were extracted from in vitro shoot tip cultures of 31 grapevine cultivars affected with rupestris stem pitting (RSP) disease and from cultures of 11 RSPfree cultivars, 4 of which were disease-free, 2 of which were fleck-affected and 5 of which were grapevine leafroll disease-affected. Analysis of the extracts by polyacrylamide slab gel electrophoresis showed that 21 of the 31 RSP-affected cultivars contained a previously unreported nucleic acid which was absent from the RSP-free controls. Nuclease digestions showed that the nucleic acid was double-stranded RNA (dsRNA). The apparent size of the dsRNA was inconsistent with that expected for either a viroid or a closterovirus. The observation that 10 of the 31 RSP-affected cultivars lacked this dsRNA is consistent with the view that there may be more than one 'RSP-like' disease. The dsRNA detected in this investigation may be associated with one of these diseases

Phospholipase A2 regulation of bovine endometrial (BEND) cell prostaglandin production

Background Prostaglandins (PG), produced by the uterine endometrium, are key regulators of several reproductive events, including estrous cyclicity, implantation, pregnancy maintenance and parturition. Phospholipase A2 (PLA2) catalyzes the release of arachidonic acid from membrane phospholipids, the rate-limiting step in PG biosynthesis. The bovine endometrial (BEND) cell line has served as a model system for investigating regulation of signaling mechanisms involved in uterine PG production but information concerning the specific PLA2 enzymes involved and their role in regulation of this process is limited. The objectives of this investigation were to evaluate the expression and activities of calcium-dependent group IVA (PLA2G4A) and calcium-independent group VI (PLA2G6) enzymes in the regulation of BEND cell PG production. Methods Cells were grown to near-confluence and treated with phorbol 12, 13 dibutyrate (PDBu), interferon-tau (IFNT), the PLA2G4A inhibitor pyrrolidine-1 (PYR-1), the PLA2G6 inhibitor bromoenol lactone (BEL) and combinations of each. Concentrations of PGF2alpha and PGE2 released into the medium were determined. Western blot analysis was performed on cellular protein to determine effects of treatment on expression of PLA2G4A, PLA2G6 and PLA2G4C. PLA2 assays were performed on intact cells by measuring arachidonic acid and linoleic acid release and group-specific PLA2 activity assays were performed on cell lysates. Results BEND cells produced about 10-fold more PGE2 than PGF2alpha under resting conditions. Production of both PGs increased significantly in response to PDBu-stimulation. PYR-1 significantly diminished production of both PGs by resting cells and abolished the stimulatory effect of PDBu. BEL stimulated production of both PGs. IFNT reduced both PGE2 and PGF2alpha production by resting cells and diminished PDBu stimulation of PG production. Conversely, IFNT did not significantly reduce BEL stimulation of PG production. Cellular expression of PLA2G4A was enhanced by PDBu and this response was diminished by IFNT. Expression of PLA2G6 was not observed to be affected by treatments and no PLA2G4C expression was observed. Arachidonic acid release from intact cells was significantly increased by PDBu and this effect was attenuated by PYR-1 but not by BEL. Release of linoleic acid from intact cells was stimulated by PDBu and inhibited by BEL but not PYR-1. Group specific PLA2-activity assays demonstrated both PLA2G4A and PLA2G6 activity. Conclusion Results from this study demonstrate that PGE2 and PGF2-alpha production by BEND cells is mediated by the activity and expression of PLA2G4A. Interferon-tau treatment diminished expression of PLA2G4A and PG production. BEND cells were shown to express PLA2G6 but, unlike primary or early passage luminal bovine endometrial cells, stimulation of PLA2G6 activity was not associated with increased PG production

Distinct phospholipase A2 enzymes regulate prostaglandin E2 and F2alpha production by bovine endometrial epithelial cells

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Presence of Transcription Factor OCT4 Limits Interferon-tau Expression during the Pre-attachment Period in Sheep

Interferon-tau (IFNT) is thought to be the conceptus protein that signals maternal recognition of pregnancy in ruminants. We and others have observed that OCT4 expression persists in the trophectoderm of ruminants; thus, both CDX2 and OCT4 coexist during the early stages of conceptus development. The aim of this study was to examine the effect of CDX2 and OCT4 on IFNT gene transcription when evaluated with other transcription factors. Human choriocarcinoma JEG-3 cells were cotransfected with an ovine IFNT (-654-bp)-luciferase reporter (-654-IFNT-Luc) construct and several transcription factor expression plasmids. Cotransfection of the reporter construct with Cdx2, Ets2 and Jun increased transcription of -654-IFNT-Luc by about 12-fold compared with transfection of the construct alone. When cells were initially transfected with Oct4 (0 h) followed by transfection with Cdx2, Ets2 and/or Jun 24 h later, the expression of -654-IFNT-Luc was reduced to control levels. OCT4 also inhibited the stimulatory activity of CDX2 alone, but not when CDX2 was combined with JUN and/or ETS2. Thus, when combined with the other transcription factors, OCT4 exhibited little inhibitory activity towards CDX2. An inhibitor of the transcriptional coactivator CREB binding protein (CREBBP), 12S E1A, reduced CDX2/ETS2/JUN stimulated -654-IFNT-Luc expression by about 40%, indicating that the formation of an appropriate transcription factor complex is required for maximum expression. In conclusion, the presence of OCT4 may initially minimize IFNT expression; however, as elongation proceeds, the increasing expression of CDX2 and formation of the transcription complex leads to greatly increased IFNT expression, resulting in pregnancy establishment in ruminants

The remarkably low affinity of CD4/peptide-major histocompatibility complex class II protein interactions

The αβ T-cell co-receptor CD4 enhances immune responses more than one million-fold in some assays, and yet the affinity of CD4 for its ligand, peptide-major histocompatibility class II (pMHC II) on antigen-presenting cells, is so weak that it was previously unquantifiable. Here, we report that a soluble form of CD4 failed to bind detectably to pMHC II in surface plasmon resonance-based assays, establishing a new upper limit for the solution affinity at 2.5 mM. However, when presented multivalently on magnetic beads, soluble CD4 bound pMHC II-expressing B cells, confirming that it is active and allowing mapping of the native co-receptor binding site on pMHC II. Whereas binding was undetectable in solution, the affinity of the CD4/pMHC II interaction could be measured in two dimensions (2D) using CD4- and adhesion molecule-functionalized, supported lipid bilayers, yielding a 2D dissociation constant, Kd, of ~5000 molecules/μm2. This value is 2-3 orders of magnitude higher than previously measured 2D Kd values for interacting leukocyte surface proteins. Calculations indicated, however, that CD4/pMHC II binding would increase rates of T-cell receptor (TCR) complex phosphorylation by three-fold via the recruitment of Lck, with only a small, 2-20% increase in the effective affinity of the TCR for pMHC II. The affinity of CD4/pMHC II therefore appears to be set at a value that increases T-cell sensitivity by enhancing phosphorylation, without compromising ligand discrimination.This work was supported by the Wellcome Trust and the UK Medical Research Council. PJ was supported by grants from the Swedish Research Council (number: 623-2014- 6387 and 621-2014-3907). OD is supported by a Sir Henry Dale Fellowship jointly funded by the Wellcome Trust and the Royal Society (Grant Number: 098363)

Comparison of peptide-major histocompatibility complex tetramers and dextramers for the identification of antigen-specific T cells

Fluorochrome-conjugated peptide–major histocompatibility complex (pMHC) multimers are widely used for flow cytometric visualization of antigen-specific T cells. The most common multimers, streptavidin–biotin-based ‘tetramers’, can be manufactured readily in the laboratory. Unfortunately, there are large differences between the threshold of T cell receptor (TCR) affinity required to capture pMHC tetramers from solution and that which is required for T cell activation. This disparity means that tetramers sometimes fail to stain antigen-specific T cells within a sample, an issue that is particularly problematic when staining tumour-specific, autoimmune or MHC class II-restricted T cells, which often display TCRs of low affinity for pMHC. Here, we compared optimized staining with tetramers and dextramers (dextran-based multimers), with the latter carrying greater numbers of both pMHC and fluorochrome per molecule. Most notably, we find that: (i) dextramers stain more brightly than tetramers; (ii) dextramers outperform tetramers when TCR–pMHC affinity is low; (iii) dextramers outperform tetramers with pMHC class II reagents where there is an absence of co-receptor stabilization; and (iv) dextramer sensitivity is enhanced further by specific protein kinase inhibition. Dextramers are compatible with current state-of-the-art flow cytometry platforms and will probably find particular utility in the fields of autoimmunity and cancer immunology

Cancer antigen discovery is enabled by RNA-sequencing of highly purified malignant and non-malignant cells

Purpose: Broadly expressed, highly differentiated tumor-associated antigens (TAA) can elicit anti-tumor immunity. However, vaccines targeting TAAs have demonstrated disappointing clinical results, reflecting poor antigen selection and/or immunosuppressive mechanisms. Experimental design: Here, a panel of widely expressed, novel colorectal TAAs were identified by performing RNA sequencing of highly purified colorectal tumor cells in comparison to patient-matched colonic epithelial cells; tumor cell purification was essential to reveal these genes. Candidate TAA protein expression was confirmed by immunohistochemistry, and pre-existing T cell immunogenicity towards these antigens tested. Results: The most promising candidate for further development is DNAJB7 [DnaJ heat shock protein family (Hsp40) member B7], identified here as a novel cancer-testis antigen. It is expressed in many tumors and is strongly immunogenic in patients with cancers originating from a variety of sites. DNAJB7-specific T cells were capable of killing colorectal tumor lines in vitro, and the IFN-gamma+ response was markedly magnified by control of immunosuppression with cyclophosphamide in cancer patients. Conclusion: This study highlights how prior methods that sequence whole tumor fractions (i.e. inclusive of alive/dead stromal cells) for antigen identification may have limitations. Through tumor cell purification and sequencing, novel candidate TAAs have been identified for future immunotherapeutic targeting

Monitoring regulatory T cells in clinical samples: consensus on an essential marker set and gating strategy for regulatory T cell analysis by flow cytometry

Regulatory T cell (Treg)-mediated immunosuppression is considered a major obstacle for successful cancer immunotherapy. The association between clinical outcome and Tregs is being studied extensively in clinical trials, but unfortunately, no consensus has been reached about (a) the markers and (b) the gating strategy required to define human Tregs in this context, making it difficult to draw final conclusions. Therefore, we have organized an international workshop on the detection and functional testing of Tregs with leading experts in the field, and 40 participants discussing different analyses and the importance of different markers and context in which Tregs were analyzed. This resulted in a rationally composed ranking list of “Treg markers”. Subsequently, the proposed Treg markers were tested to get insight into the overlap/differences between the most frequently used Treg definitions and their utility for Treg detection in various human tissues. Here, we conclude that the CD3, CD4, CD25, CD127, and FoxP3 markers are the minimally required markers to define human Treg cells. Staining for Ki67 and CD45RA showed to provide additional information on the activation status of Tregs. The use of markers was validated in a series of PBMC from healthy donors and cancer patients, as well as in tumor-draining lymph nodes and freshly isolated tumors. In conclusion, we propose an essential marker set comprising antibodies to CD3, CD4, CD25, CD127, Foxp3, Ki67, and CD45RA and a corresponding robust gating strategy for the context-dependent analysis of Tregs by flow cytometry